Magnetically coupled pressure sensor

ABSTRACT

Measurement of pressure of a fluid in a vessel using a cantilever spring in the vessel; a magnet connected to the cantilever spring in the vessel; an electromagnet outside of the vessel operatively connected to the magnet and the cantilever spring in the vessel, wherein the electromagnet induces movement of the magnet and the cantilever spring in the vessel, and wherein the movement is related to the pressure of the fluid in the vessel; a receiving coil operatively positioned relative to the magnet, wherein movement of the cantilever spring and the magnet in the vessel creates an electromotive response in the coil; and a controller analyzer connected to the receiving coil, wherein the controller analyzer uses the electromotive response in the coil for measuring the pressure of the fluid in the vessel.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Division of Application No. 16/393,407filed Apr. 24, 2019, entitled “MAGNETICALLY COUPLED PRESSURE SENSOR,”the disclosure of which is hereby incorporated by reference in itsentirety for all purposes.

STATEMENT AS TO RIGHTS TO APPLICATIONS MADE UNDER AND FEDERALLYSPONSORED RESEARCH DEVELOPMENT

The This invention was made with Government support under Contract No.DE-AC52-07NA27344 awarded by the United States Department of Energy. TheGovernment has certain rights in the invention.

BACKGROUND Field of Endeavor

The present application relates to a method and system of detectingpressure within a closed volume, and more particularly to anon-penetrating method and system using an oscillating cantilever todetect pressure in a closed volume through a wall defining the closedvolume.

State of Technology

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Pressure volumes, pipes, conduits, biologic systems and environmentsoften require that data be accessed without interruption of theintegrity of the contained volume. However, it is often difficult toaccess data from a pressure sensor in such environments. Prior art hasattempted hermetic sealing to pass wires or optic fibers through thewall of the volume, but this is sometimes unacceptable or prone tofailure.

SUMMARY

Features and advantages of the disclosed apparatus, systems, and methodswill become apparent from the following description. Applicant isproviding this description, which includes drawings and examples ofspecific embodiments, to give a broad representation of the apparatus,systems, and methods. Various changes and modifications within thespirit and scope of the application will become apparent to thoseskilled in the art from this description and by practice of theapparatus, systems, and methods. The scope of the apparatus, systems,and methods is not intended to be limited to the particular formsdisclosed and the application covers all modifications, equivalents, andalternatives falling within the spirit and scope of the apparatus,systems, and methods as defined by the claims.

The inventors have developed apparatus, systems, and methods formeasuring pressure of a fluid in a vessel. The apparatus, systems, andmethods are capable of measuring gas or fluid pressure within a closedvolume by magnetically coupling through the wall that defines thatvolume. In various embodiments the apparatus, systems, and methods arebased on an oscillating cantilever that interacts with the contents ofthe volume. The dynamics of the oscillation depend on the materialaround the cantilever. The cantilever's motion is driven and interpretedby external electronics that require no direct connection to thecantilever. In various embodiments the apparatus, systems, and methodsare based on a sensor located inside of the vessel for sensing theunknown internal pressure of the fluid inside the vessel and a magneticinduction communication system having a first induction coil locatedinside of the vessel wall and a second induction coil located outside ofthe vessel wall wherein the magnetic induction communication systemcommunicates the sensed unknown internal pressure of the fluid insidethe vessel from the sensor to the first induction coil and from thefirst induction coil to the second induction coil and from the secondinduction coil to the receiving unit and from the receiving unit to thecontroller analyzer for measuring the pressure of the fluid in thevessel.

The apparatus, systems, and methods address the difficulty of accessingdata from a pressure sensor in particular environments. Pressurevolumes, pipes, conduits, biologic systems and environments oftenrequire that data be accessed without interruption of the integrity ofthe contained volume. Prior art has attempted hermetic sealing to passwires or optic fibers through the wall of the volume, but this issometimes unacceptable or prone to failure. The non-penetrating schemeas proposed here addresses these issues. Coupled with this concept ofnon-penetration is a means of detecting pressure with use of anoscillating cantilever. The overall system is very simple and arguablyhighly robust for long term use and potentially low cost for disposableapplications. The apparatus, systems, and methods are useful formeasuring pressure within a closed volume or across a barrier where nopenetrations of that barrier are required.

The apparatus, systems, and methods are susceptible to modifications andalternative forms. Specific embodiments are shown by way of example. Itis to be understood that the apparatus, systems, and methods are notlimited to the particular forms disclosed. The apparatus, systems, andmethods cover all modifications, equivalents, and alternatives fallingwithin the spirit and scope of the application as defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and constitute apart of the specification, illustrate specific embodiments of theapparatus, systems, and methods and, together with the generaldescription given above, and the detailed description of the specificembodiments, serve to explain the principles of the apparatus, systems,and methods.

FIG. 1 illustrates an embodiment of Applicants' apparatus, systems, andmethods.

FIG. 2 illustrates another embodiment of Applicants' apparatus, systems,and methods.

FIG. 3 illustrates yet another embodiment of Applicants' apparatus,systems, and methods.

FIG. 4 illustrates an embodiment of Applicants' apparatus, systems, andmethods wherein the receiving coil is on one side of the vessel.

FIG. 5 illustrates the cantilever in greater detail.

FIG. 6 illustrates another embodiment of Applicants' apparatus, systems,and methods utilizing a sensor with the shape of a tuning fork.

FIG. 7 illustrates an embodiment of Applicants' apparatus, systems, andmethods utilizing a sensor with the shape of a tuning fork locatedinside a vessel and a receiving coil located outside the vessel.

FIG. 8 illustrates yet another embodiment of Applicants' apparatus,systems, and methods utilizing a sensor with the shape of a tuning forkinside a vessel and an excitation coil and a receiving coil outside thevessel.

FIG. 9 illustrates an embodiment of Applicants' apparatus, systems, andmethods utilizing a sensor and a transmitting coil inside a vessel and areceiving coil outside the vessel.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Referring to the drawings, to the following detailed description, and toincorporated materials, detailed information about the apparatus,systems, and methods is provided including the description of specificembodiments. The detailed description serves to explain the principlesof the apparatus, systems, and methods. The apparatus, systems, andmethods are susceptible to modifications and alternative forms. Theapplication is not limited to the particular forms disclosed. Theapplication covers all modifications, equivalents, and alternativesfalling within the spirit and scope of the apparatus, systems, andmethods as defined by the claims.

The inventors have developed apparatus, systems, and methods formeasuring pressure of a fluid in a vessel. The inventors apparatus,systems, and methods include a cantilever spring in the vessel; a magnetconnected to the cantilever spring in the vessel; an electromagnetoutside of the vessel operatively connected to the magnet and thecantilever spring in the vessel, wherein the electromagnet inducesmovement of the magnet and the cantilever spring in the vessel, andwherein the movement is related to the pressure of the fluid in thevessel; a receiving coil operatively positioned relative to the magnet,wherein movement of the cantilever spring and the magnet in the vesselcreates an electromotive response in the coil; and a controller analyzerconnected to the receiving coil, wherein the controller analyzer usesthe electromotive response in the coil for measuring the pressure of thefluid in the vessel. The controller analyzer is connected to theelectromagnet and adapted to induce harmonic oscillation of the magnetin the vessel wherein the harmonic oscillation of the magnet in thevessel is related to the pressure of the fluid in the vessel. Thereceiving coil is a magnetic field detector adapted to detect theharmonic oscillation of the magnet in the vessel and create anelectromotive response in the coil related to the pressure of the fluidin the vessel.

This apparatus, systems, and methods provide a sensor that measurespressure in a closed volume. The sensor has two components, one thatsits inside the closed volume and one that sits outside the closedvolume. The two components “communicate” through magnetic coupling only.The coupling can pass through many materials including a closed systemthat acts as a Faraday cage.

The internal component can take the form of a metallic cantilever. Apermanent magnet is mounted at the end of the cantilever. The cantileveris designed to have specific vibrational modes that relate to itsmagnetic coupling and drive. Finally, the cantilever is also designed tohave a cross sectional profile that interacts with the gas or fluidenvironment it sits in. This interaction provides viscous and massdamping that is the means of pressure sensing.

The external component is electrically driven. It consists of one or twocoils. The two-coil version is the simplest incarnation. The drivingcoil is an electromagnet that produces a driving magnetic field thatpushes and/or pulls the permanent magnet at the end of the cantilever.This driving mechanism can be a one-time pulse similar to plucking theend of the cantilever or an oscillating, continuous signal that activelydrives the cantilever.

The second coil interacts with the changing magnetic field from themoving permanent magnet on the cantilever. The changing magnetic fieldin the ‘receiving coil’ generates an electric current in that coil.Monitoring this current describes the cantilever motion.

As the pressure in the closed volume changes, the natural frequency ofcantilever changes due to the gas damping and added mass. Measuring thecantilever ring down from a ‘pluck’ or finding its new natural frequencyby sweeping the driving field, the pressure can be inferred from acalibration.

Referring to FIG. 1, an illustrative view shows an embodiment ofApplicants' apparatus, systems, and methods. This embodiment isidentified generally by the reference numeral 100. FIG. 1 is anillustrative side view Applicant's magnetically coupled pressure sensorfor measuring pressure of a fluid in a vessel. The components ofApplicant's pressure sensor apparatus, systems, and methods in FIG. 1are listed below.

-   -   100—Magnetically coupled pressure sensor system (MCPSS),    -   102—Vessel,    -   104—Computer controller analyzer,    -   106—Power source,    -   108—Electromagnet,    -   110—Receiving coil,    -   112—Data acquisition module,    -   114—Cantilever spring,    -   116—Magnet,    -   118—Motion arrows, and    -   120—Medium being measured.

The description of the structural components of the Applicant's pressuresensor 100 having been completed, the operation and additionaldescription of the Applicant's pressure sensor will now be considered ingreater detail. The magnetically coupled pressure sensor 100 formeasuring pressure of a fluid 120 in a vessel 102 uses a cantileverspring 114 located in the vessel 102. A magnet 116 is connected to thecantilever spring 114 in the vessel. In this embodiment the magnet 116is a discrete magnet positioned at far end of the cantilever spring 114.

An electromagnet 108 outside of the vessel 102 is operatively connectedto the magnet 116 and the cantilever spring 114 in the vessel 102. Theelectromagnet 108 induces movement 118 of the magnet 116 and thecantilever spring 114 in the vessel 102. The movement 118 is related tothe pressure of the fluid 120 in the vessel 102.

A receiving coil 110 is operatively positioned relative to the magnet116. Movement 118 of the cantilever spring 114 and the magnet 116 in thevessel 102 creates an electromotive response in the coil 110. A computercontroller analyzer 104 is connected to the receiving coil 110. Thecomputer controller analyzer 104 uses the electromotive response in thecoil 110 for measuring the pressure of the fluid 120 in the vessel 102.

The computer controller analyzer 104 is connected to the electromagnet108 and adapted to induce harmonic oscillation of the magnet 116 in thevessel 102. The harmonic oscillation of the magnet 116 in the vessel 102is related to the pressure of the fluid 120 in the vessel 102. Thereceiving coil 110 is a magnetic field detector adapted to detect theharmonic oscillation of the magnet 116 in the vessel 102 and create anelectromotive response in the coil 110 related to the pressure of thefluid in the vessel. The pressure of the fluid 120 in the vessel 102will influence the ring-down of the cantilever by changing the dampednatural frequency of oscillation and the pressure changes the rate ofring down.

Referring to FIG. 2, an illustrative view shows an embodiment ofApplicants' apparatus, systems, and methods. This embodiment isidentified generally by the reference numeral 200. FIG. 2 is anillustrative side view Applicant's magnetically coupled pressure sensorfor measuring pressure of a fluid in a vessel 200. The components ofFIG. 2 are listed below.

-   -   200—Magnetically coupled pressure sensor system (MCPSS),    -   202—Vessel,    -   204—Computer controller analyzer,    -   206—Power source,    -   208—Electromagnet,    -   210—Receiving coil,    -   212—Data acquisition module,    -   214—Cantilever spring,    -   216—Magnet,    -   218—Motion arrows, and    -   220—Medium being measured.

The description of the structural components of the embodiment ofApplicant's pressure sensor 200 having been completed, the operation andadditional description of the Applicant's pressure sensor 200 will nowbe considered in greater detail. The magnetically coupled pressuresensor 200 for measuring pressure of a fluid in a vessel uses acantilever spring 214 located in the vessel. A magnet 216 is connectedto the cantilever spring 214 in the vessel. In this embodiment themagnet 216 extends the entire length of the cantilever spring 214.

An electromagnet outside of the vessel is operatively connected to themagnet 216 and the cantilever spring 214 in the vessel. Theelectromagnet induces movement of the magnet 216 and the cantileverspring 214 in the vessel. The movement is related to the pressure of thefluid in the vessel.

A receiving coil is operatively positioned relative to the magnet 216.Movement of the cantilever spring 214 and the magnet 216 in the vesselcreates an electromotive response in the coil. A computer controlleranalyzer is connected to the receiving coil. The computer controlleranalyzer uses the electromotive response in the coil for measuring thepressure of the fluid in the vessel.

The computer controller analyzer is connected to the electromagnet andadapted to induce harmonic oscillation of the magnet 216 in the vessel.The harmonic oscillation of the magnet 216 in the vessel is related tothe pressure of the fluid in the vessel. The receiving coil is amagnetic field detector adapted to detect the harmonic oscillation ofthe magnet 216 in the vessel and create an electromotive response in thecoil related to the pressure of the fluid in the vessel.

Referring to FIG. 3, an illustrative view shows an embodiment ofApplicants' apparatus, systems, and methods. This embodiment isidentified generally by the reference numeral 300. FIG. 3 is anillustrative side view Applicant's magnetically coupled pressure sensorfor measuring pressure of a fluid in a vessel. The components of FIG. 3that differ from the FIG. 1 components are listed below.

-   -   300—Magnetically coupled pressure sensor system (MCPSS),    -   302—Vessel,    -   304—Computer controller analyzer,    -   306—Power source,    -   308—Electromagnet,    -   310—Receiving coil,    -   312—Data acquisition module,    -   314—Cantilever spring,    -   316—Magnet,    -   318—Motion arrows,    -   320—Medium being measured,    -   322—Particles entrained in the medium, and    -   324—Coating on cantilever to prevent particles entrained in the        medium from adhering to the cantilever,

The description of the structural components of the embodiment ofApplicant's pressure sensor 300 having been completed, the operation andadditional description of the Applicant's pressure sensor 300 will nowbe considered in greater detail. The magnetically coupled pressuresensor 300 for measuring pressure of a fluid in a vessel uses acantilever spring 314 located in the vessel. Particles 322 are entrainedin the medium. A magnet 316 is connected to the cantilever spring 314 inthe vessel. In this embodiment the magnet 316 is a discrete magnetpositioned at far end of the cantilever spring 314. A coating 324 oncantilever helps prevent particles 322 entrained in the medium fromadhering to the cantilever,

An electromagnet outside of the vessel is operatively connected to themagnet 316 and the cantilever spring 314 in the vessel. Theelectromagnet induces movement of the magnet 316 and the cantileverspring 314 in the vessel. The movement is related to the pressure of thefluid in the vessel.

A receiving coil is operatively positioned relative to the magnet 316.Movement of the cantilever spring 314 and the magnet 316 in the vesselcreates an electromotive response in the coil. A computer controlleranalyzer is connected to the receiving coil. The computer controlleranalyzer uses the electromotive response in the coil for measuring thepressure of the fluid in the vessel.

The computer controller analyzer is connected to the electromagnet andadapted to induce harmonic oscillation of the magnet 316 in the vessel.The harmonic oscillation of the magnet 316 in the vessel is related tothe pressure of the fluid in the vessel. The receiving coil is amagnetic field detector adapted to detect the harmonic oscillation ofthe magnet 316 in the vessel and create an electromotive response in thecoil related to the pressure of the fluid in the vessel.

Referring to FIG. 4, an illustrative view shows an embodiment ofApplicants' apparatus, systems, and methods wherein the receiving coilis on one side of the vessel. This embodiment is identified generally bythe reference numeral. FIG. 4 is an illustrative side view Applicant'smagnetically coupled pressure sensor for measuring pressure of a fluidin a vessel 402. The components of Applicant's pressure sensorapparatus, systems, and methods in FIG. 4 are listed below.

-   -   400—Magnetically coupled pressure sensor system (MCPSS),    -   402—Vessel,    -   404—Computer controller analyzer,    -   406—Power source,    -   408—Electromagnet,    -   410—Receiving coil,    -   412—Data acquisition module,    -   414—Cantilever spring,    -   416—Magnet,    -   418—Motion arrows, and    -   420—Medium being measured.

The description of the structural components of the Applicant's pressuresensor 400 having been completed, the operation and additionaldescription of the Applicant's pressure sensor will now be considered ingreater detail. The magnetically coupled pressure sensor 400 formeasuring pressure of a fluid 420 in a vessel 402 uses a cantileverspring 414 located in the vessel 402. A magnet 416 is connected to thecantilever spring 414 in the vessel. In this embodiment the magnet 416is a discrete magnet positioned at far end of the cantilever spring 414.

An electromagnet 408 outside of the vessel 402 is operatively connectedto the magnet 416 and the cantilever spring 414 in the vessel 402. Theelectromagnet 408 induces movement 418 of the magnet 416 and thecantilever spring 414 in the vessel 402. The movement 418 is related tothe pressure of the fluid 420 in the vessel 402.

A receiving coil 410 is operatively positioned relative to the magnet416. The receiving coil 410 in this embodiment is on one side of thevessel 402. Movement 418 of the cantilever spring 414 and the magnet 416in the vessel 402 creates an electromotive response in the coil 410. Acomputer controller analyzer 404 is connected to the receiving coil 410.The computer controller analyzer 404 uses the electromotive response inthe coil 410 for measuring the pressure of the fluid 420 in the vessel402.

The computer controller analyzer 404 is connected to the electromagnet408 and adapted to induce harmonic oscillation of the magnet 416 in thevessel 402. The harmonic oscillation of the magnet 416 in the vessel 402is related to the pressure of the fluid 420 in the vessel 402. Thereceiving coil 410 is a magnetic field detector adapted to detect theharmonic oscillation of the magnet 416 in the vessel 402 and create anelectromotive response in the coil 410 related to the pressure of thefluid in the vessel.

Referring to FIG. 5, an illustrative view shows the cantilever ingreater detail. This embodiment is identified generally by the referencenumeral 500. The components of Applicant's pressure sensor apparatus,systems, and methods in FIG. 5 are listed below.

-   -   500—Cantilever spring system,    -   502—Vessel,    -   504—Attachment,    -   506—Cantilever spring,    -   508—Width,    -   510—Thickness, and    -   512—Length.

The description of the structural components of the Applicant'scantilever spring system 500 having been completed, the operation andadditional description of the Applicant's cantilever spring system 500will now be considered in greater detail. Applicant's apparatus,systems, and methods provide a magnetically coupled pressure sensor formeasuring pressure of a fluid in a vessel 502 uses a cantilever spring506 located in the vessel 502. The fixed end of the cantilever spring506 is connected to the vessel 502 by an attachment. The moveable springend of the cantilever spring 506 is within the vessel 502. Thecantilever spring 506 has a width 508, a thickness 510, and a length512.

As previously explained an electromagnet outside of the vessel 502 isoperatively connected to the magnet on the cantilever spring 506 in thevessel 502. The electromagnet induces movement of the magnet and thecantilever spring 506 in the vessel 502. The movement is related to thepressure of the fluid in the vessel 502. A receiving coil is operativelypositioned relative to the magnet. Movement of the cantilever spring 506and the magnet in the vessel 502 creates an electromotive response inthe receiving coil. A computer controller analyzer uses theelectromotive response in the receiving coil for measuring the pressureof the fluid in the vessel 502. The harmonic oscillation of the magnetin the vessel 502 is related to the pressure of the fluid in the vessel502. The receiving coil is a magnetic field detector adapted to detectthe harmonic oscillation of the magnet in the vessel 502 and create anelectromotive response in the coil related to the pressure of the fluidin the vessel.

Referring to FIG. 6, an illustrative view shows another embodiment ofApplicants' apparatus, systems, and methods utilizing a sensor with theshape of a tuning fork. This embodiment is identified generally by thereference numeral 600. The components of Applicant's embodiment 600illustrated in FIG. 6 are listed below.

-   -   602—Vessel,    -   604—Attachment to vessel,    -   606—Sensor with the shape of a tuning fork,    -   608—Tuning fork handle,    -   610—Tuning fork portion,    -   612—Magnets,    -   614—Magnet field,    -   616—Ring down, and    -   618—Fluid being measured.

The description of the structural components of the Applicants'apparatus, systems, and methods utilizing a sensor with the shape of atuning fork having been completed, the operation and additionaldescription of the embodiment 600 will now be considered in greaterdetail. Applicant's apparatus, systems, and methods 600 provide amagnetically coupled pressure sensor 606 in the shape of a tuning fork.The sensor 606 measures the pressure of a fluid 618 in a vessel 602using a cantilever spring sensor 606 having the shape of a tuning fork.The sensor 606 has a tuning fork handle 608 and a tuning fork portion610. Magnets 612 are connected to the tuning fork portion 610.

As previously illustrated and describe, a receiving coil is operativelypositioned relative to the magnets 612. Movement of the tuning forkhandle 608 and the tuning fork portion 610 in the vessel 602 creates anelectromotive response in the receiving coil. A computer controlleranalyzer is connected to the receiving coil. The computer controlleranalyzer uses the electromotive response in the coil for measuring thepressure of the fluid 618 in the vessel 602.

Applicants' apparatus, systems, and methods can measure the pressure ofthe fluid 618 using harmonic oscillation of the magnets 612 in thevessel 602. Applicants' apparatus, systems, and methods can also measurethe pressure of the fluid 618 using ring down 616. Ring-down measurementis a well known form of measurement. The ring down 616 measurement ofthe pressure of the fluid 618 in the vessel 602 is achieved bydetermining the time between initiation of movement of the sensor 606and when the movement stops. The ring down time is related to thepressure of the fluid 618 in the vessel 602. The tuning fork 610 offersthe advantage of a system with less loss to the vessel as theoscillatory energy is better contained within the tuning fork 610 due toits mechanical balance. Additionally, if the blades of the tuning fork610 are very close together, squeeze film damping can improve thesensitivity of the device as the viscous loading of the oscillating beamis exaggerated.

Referring to FIG. 7, an illustrative view shows another embodiment ofApplicants' apparatus, systems, and methods. This embodiment utilizes asensor with the shape of a tuning fork with the sensor located inside avessel and a receiving coil located outside the vessel. This embodimentis identified generally by the reference numeral 700. The components ofApplicant's embodiment 700 illustrated in FIG. 7 are listed below.

-   -   702—Vessel,    -   704—Attachment to vessel,    -   706—Sensor with the shape of a tuning fork,    -   708—Tuning fork handle,    -   710—Tuning fork portion,    -   712—Magnets,    -   714—Excitation coil,    -   716—Pick up coil, and    -   718—Fluid being measured.

The description of the structural components of the Applicants'apparatus, systems, and methods utilizing a sensor with the shape of atuning fork having been completed, the operation and additionaldescription of the embodiment 700 will now be considered in greaterdetail. Applicant's apparatus, systems, and methods 700 provide amagnetically coupled pressure sensor 706 in the shape of a tuning fork.The sensor 706 measures the pressure of a fluid 718 in a vessel 702using a cantilever spring sensor 706 having the shape of a tuning fork.The sensor 706 has a tuning fork handle 708 and a tuning fork portion710. Magnets 712 are connected to the tuning fork portion 710.

An excitation coil 714 is located outside of the vessel 702 and isoperatively positioned relative to the sensor 706. A receiving coil 716is located outside of the vessel 702 and is operatively positionedrelative to the sensor 706. Movement of the sensor 706 in the vessel 702is initiated by the excitation coil 714. Movement of the sensor 706 inthe vessel 702 creates an electromotive response in the receiving coil716.

As previously illustrated and explained, a computer controller analyzeris connected to the receiving coil 716. The computer controller analyzeruses the electromotive response in the coil 716 for measuring thepressure of the fluid 718 in the vessel 702.

Applicants' apparatus, systems, and methods can measure the pressure ofthe fluid 718 using harmonic oscillation of the magnets 712 in thevessel 702. Applicants' apparatus, systems, and methods can also measurethe pressure of the fluid 718 using ring down. Ring-down measurement isa well known form of measurement. The ring down measurement of thepressure of the fluid 718 in the vessel 702 is achieved by determiningthe time between initiation of movement of the sensor 706 and when themovement stops. The ring down time is related to the pressure of thefluid 718 in the vessel 702.

Referring to FIG. 8, an illustrative view shows another embodiment ofApplicants' apparatus, systems, and methods. This embodiment utilizes asensor with the shape of a tuning fork with the sensor located inside avessel and an excitation coil and a receiving coil located next to eachother outside the vessel. This embodiment is identified generally by thereference numeral 800. The components of Applicant's embodiment 800illustrated in FIG. 8 are listed below.

-   -   802—Vessel,    -   804—Attachment to vessel,    -   806—Sensor with the shape of a tuning fork,    -   808—Tuning fork handle,    -   810—Tuning fork portion,    -   812—Magnets,    -   814—Excitation coil,    -   816—Pick up coil, and    -   818—Fluid being measured.

The description of the structural components of the Applicants'apparatus, systems, and methods utilizing a sensor with the shape of atuning fork having been completed, the operation and additionaldescription of the embodiment 800 will now be considered in greaterdetail. Applicant's apparatus, systems, and methods 800 provide amagnetically coupled pressure sensor 806 in the shape of a tuning fork.The sensor 806 measures the pressure of a fluid 818 in a vessel 802using a cantilever spring sensor 806 having the shape of a tuning fork.The sensor 806 has a tuning fork handle 808 and a tuning fork portion810. Magnets 812 are connected to the tuning fork portion 810.

An excitation coil 814 and a receiving coil (pick up coil) 816 arelocated outside of the vessel 802 and are operatively positionedrelative to the sensor 806. The excitation coil 814 and the receivingcoil 816 are located next to each other outside the vessel 802. Movementof the sensor 806 in the vessel 802 is initiated by the excitation coil814. Movement of the sensor 806 in the vessel 802 creates anelectromotive response in the receiving coil 816.

As previously illustrated and explained, a computer controller analyzeris connected to the receiving coil 816. The computer controller analyzeruses the electromotive response in the coil 816 for measuring thepressure of the fluid 818 in the vessel 802.

Applicants' apparatus, systems, and methods can measure the pressure ofthe fluid 818 using harmonic oscillation of the magnets 812 in thevessel 802. Applicants' apparatus, systems, and methods can also measurethe pressure of the fluid 818 using ring down. Ring-down measurement isa well known form of measurement. The ring down measurement of thepressure of the fluid 818 in the vessel 802 is achieved by determiningthe time between initiation of movement of the sensor 806 and when themovement stops. The ring down time is related to the pressure of thefluid 818 in the vessel 802.

Referring to FIG. 9, an illustrative view shows an embodiment ofApplicants' apparatus, systems, and methods that utilizes a sensorinside a vessel and a receiving coil outside the vessel. The apparatus,systems and methods are designated generally by the reference numeral900. The components of Applicant's embodiment 900 illustrated in FIG. 9are listed below.

-   -   902—Vessel wall,    -   904—Unknown internal pressure,    -   906—External pressure ambient,    -   908—Internal coil,    -   910—External coil,    -   912—Sensor    -   914—Medium being measured, and    -   916—Measuring circuit.

The description of the structural components of the Applicant'sapparatus, systems, and methods that utilizes a sensor inside a vesseland a receiving coil outside the vessel 900 having been completed, theoperation and additional description of the Applicant's apparatus,systems, and methods will now be considered in greater detail.

An unknown internal pressure 904 of a fluid 914 inside of a vessel ismeasured by sensor 912 and the measured value is transmitted through thevessel wall 902 by the internal coil 908 that is coupled to the externalcoil 910. The external pressure 906 is ambient. Measuring circuit 916receives the measurement. The sensor 912 can be a capacitive orresistive device that varies with pressure. A change in resistance orcapacitance will change the harmonic frequency of theResistor-Inductor-Capacitor (RLC) circuit. This frequency can bedetermined by scanning the driving circuit to look for resonance andthus determine the variable quantity (R or C) that is calibrated topressure. This incarnation of the device works equally well in a liquidor gas environment.

Although the description above contains many details and specifics,these should not be construed as limiting the scope of the applicationbut as merely providing illustrations of some of the presently preferredembodiments of the apparatus, systems, and methods. Otherimplementations, enhancements and variations can be made based on whatis described and illustrated in this patent document. The features ofthe embodiments described herein may be combined in all possiblecombinations of methods, apparatus, modules, systems, and computerprogram products. Certain features that are described in this patentdocument in the context of separate embodiments can also be implementedin combination in a single embodiment. Conversely, various features thatare described in the context of a single embodiment can also beimplemented in multiple embodiments separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asubcombination or variation of a subcombination. Similarly, whileoperations are depicted in the drawings in a particular order, thisshould not be understood as requiring that such operations be performedin the particular order shown or in sequential order, or that allillustrated operations be performed, to achieve desirable results.Moreover, the separation of various system components in the embodimentsdescribed above should not be understood as requiring such separation inall embodiments.

Therefore, it will be appreciated that the scope of the presentapplication fully encompasses other embodiments which may become obviousto those skilled in the art. In the claims, reference to an element inthe singular is not intended to mean “one and only one” unlessexplicitly so stated, but rather “one or more.” All structural andfunctional equivalents to the elements of the above-described preferredembodiment that are known to those of ordinary skill in the art areexpressly incorporated herein by reference and are intended to beencompassed by the present claims. Moreover, it is not necessary for adevice to address each and every problem sought to be solved by thepresent apparatus, systems, and methods, for it to be encompassed by thepresent claims. Furthermore, no element or component in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element or component is explicitly recited in the claims. Noclaim element herein is to be construed under the provisions of 35U.S.C. 112, sixth paragraph, unless the element is expressly recitedusing the phrase “means for.”

While the apparatus, systems, and methods may be susceptible to variousmodifications and alternative forms, specific embodiments have beenshown by way of example in the drawings and have been described indetail herein. However, it should be understood that the application isnot intended to be limited to the particular forms disclosed. Rather,the application is to cover all modifications, equivalents, andalternatives falling within the spirit and scope of the application asdefined by the following appended claims.

The claims are:
 1. A magnetically-coupled sensor system for detectingchanges in a measurand of a monitored space, comprising: a harmonicoscillator having a permanent magnet adapted to harmonically oscillatein the monitored space when displaced from equilibrium; a magnetic fieldsource adapted to induce harmonic oscillation of the permanent magnet inthe monitored space; and a magnetic field detector adapted to detect anoscillation frequency of the induced harmonic oscillation of thepermanent magnet, whereby a change in the measurand of the monitoredspace may be detected by comparing the oscillation frequency detected bythe magnetic field detector and a predetermined reference oscillationfrequency of the harmonic oscillator to measure a change in dampinginduced by the change in the measurand.
 2. The magnetically-coupledsensor system of claim 1, further comprising a processor operablyconnected to said magnetic field detector that is adapted to compare theoscillation frequency detected by said magnetic field detector and apredetermined reference oscillation frequency and measure a change inharmonic oscillation damping induced by and corresponding in magnitudeto the change in the measurand.
 3. The magnetically-coupled sensorsystem of claim 1 wherein said harmonic oscillator includes a cantileverspring with a free end and wherein said permanent magnet is connected tosaid free end of said cantilever spring.
 4. The magnetically-coupledsensor system of claim 1 wherein said harmonic oscillator includes acantilever spring with a length and wherein said permanent magnet extendsaid length of said cantilever spring.
 5. The magnetically-coupledsensor system of claim 1 wherein there are particles in the measurandand wherein said cantilever spring is coated with a non-stick coatingthat prevents said particles in the measurand from sticking to saidcantilever spring.
 6. The magnetically-coupled sensor system of claim 1wherein said magnetic field detector includes a receiving coil thatextends around said permanent magnet.
 7. The magnetically-coupled sensorsystem of claim 1 wherein said magnetic field detector includes areceiving coil located adjacent said permanent magnet.
 8. An apparatusfor measuring unknown internal pressure of a fluid inside of a vesselwherein the vessel has a vessel wall, comprising: a sensor locatedinside of the vessel for sensing the unknown internal pressure of thefluid inside the vessel; a receiving unit located outside of the vessel;a controller analyzer operatively connected to said receiving unit, anda magnetic induction communication system having a first induction coillocated inside of the vessel wall and a second induction coil locatedoutside of the vessel wall, wherein said magnetic inductioncommunication system is operatively connected to said sensor and saidreceiving unit and wherein said magnetic induction communication systemcommunicates said sensed unknown internal pressure of the fluid insidethe vessel from said sensor to said first induction and from said firstinduction coil to said second induction coil and from said secondinduction coil to said receiving unit and from said receiving unit tosaid controller analyzer for measuring the pressure of the fluid in thevessel.
 9. The apparatus for measuring unknown internal pressure of afluid inside of a vessel of claim 8 wherein said sensor is a resistivesensor.
 10. The apparatus for measuring unknown internal pressure of afluid inside of a vessel of claim 8 wherein said sensor is a capacitivesensor.
 11. The apparatus for measuring unknown internal pressure of afluid inside of a vessel of claim 8 wherein said sensor includes adiaphragm that responds to the unknown internal pressure of the fluidinside of the vessel.